JPH0527161B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a disc-shaped record carrier mold clamping device in an apparatus for reproducing and inspecting a disc-shaped record carrier mold.

Conventional structure and problems Disc-shaped record carrier molds are mainly made of nickel, but in order to reproduce and inspect them, it is necessary to clamp the disc-shaped record carrier molds to a rotary table with good flatness. . One of the conventional clamping devices for this purpose
One known method is to mechanically clamp the disc-shaped record carrier using a protrusion on the rotary table side that protrudes through the center positioning hole of the mold. This clamping device does not cause any problems when the mold is mechanically clamped because it does not distort the mold very much when the mold is thick, but when the mold is thinner, on the order of several hundred microns, it becomes difficult to mechanically clamp the mold. Clamping causes distortion, which not only impedes reproduction and inspection, but also causes defects in subsequent processes. Also, the third
As shown in the figure, the disc-shaped record carrier mold A generally has a bowl-shaped warpage or distortion, especially in the signal recording area (this is often the case with thin molds), so the warpage or distortion occurs when clamping. It is necessary to correct the warpage, but since the conventional clamping device described above mechanically clamps only the center portion of the mold, it has not been possible to correct the warp as a whole.

On the other hand, when reproducing signals from a disc-shaped record carrier mold, it is necessary to keep the eccentricity of the signal groove as small as possible, but in general, the eccentricity between the center hole of the disc-shaped record carrier mold and the signal groove is Due to its large size, positioning using the center hole alone is insufficient, and it is necessary to correct its eccentricity during clamping.

Purpose of the Invention The present invention solves the above-mentioned conventional drawbacks, and is capable of reliably fixing a disc-shaped record carrier mold to a rotary table with good flatness without causing distortion, and also allows recording signal grooves to be It is an object of the present invention to provide a disk-shaped record carrier mold clamping device having a mechanism capable of correcting eccentricity.

Structure of the Invention In order to achieve the above object, a disc-shaped record carrier mold clamping device of the present invention includes a rotary table for clamping a disc-shaped record carrier mold, and a means for holding the disc-shaped record carrier mold. It is composed of an upper rotary table and a lower rotary table having means for supporting and holding the upper rotary table, and the upper rotary table is configured to be movable in the radial direction on the lower rotary table.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes an upper rotary table, on which a disk-shaped record carrier mold 2 is placed. A recess 1a is formed in a portion of the upper rotary table 1 corresponding to the signal recording area of the disc-shaped record carrier mold 2, and a rubber magnet disk 3 is fixed in the recess 1a. A plurality of through holes 4 are bored at appropriate intervals on the same circumference in the protrusion 1b surrounding the outer periphery of the recess 1a of the upper rotary table 1, and the protrusion 1b
Vacuum seal rings 5a and 5b are attached to both sides in the radial direction. The upper rotary table 1 is provided with an annular exhaust groove 6a concentric with the through hole 4 at a position matching the through hole 4 at the upper end of the outer peripheral part, and another exhaust groove 6b at the upper end on the inner peripheral side thereof. It is supported on a rotary table 7. An exhaust passage 8 is provided inside the lower rotary table 7 and communicates with the exhaust grooves 6a and 6b. 9 is a hollow center boss which fits into a hole 1c drilled in the center of the upper rotary table 1, whose lower end is supported by a positioning plate 10 fixed in the center hole 7a of the lower rotary table 7; is provided so as to protrude from the upper surface of the upper rotary table 1. Reference numeral 11 denotes a positioning pin inserted into the center boss 9, which has a conical lower end, and a mortar-shaped hole 10 bored in the center of the positioning plate 10.
It is abutted and supported by a leaf spring 12 that is attached to the positioning plate 10 through the hole a. The lower rotating table 7 is fixed on a hollow rotating shaft 13.

In the above configuration, when the disc-shaped record carrier mold 2 is mounted on the upper rotary table 1 with its center hole 2a aligned with the center boss 9, it is clamped to the upper rotary table 1 by magnetic attraction of the rubber magnet disc 3.
Next, by pushing in the positioning pin 11 and aligning the tip of the positioning pin 11 with the center hole 10a of the positioning plate 10, the center of the upper rotary table 1 with the disc-shaped record carrier mold 2 clamped thereon is determined.

Here, when the exhaust path 8 is connected to an external vacuum exhaust device (not shown) and this vacuum exhaust device is operated, the inside of the exhaust path 8, the exhaust grooves 6a and 6b, and the through hole 4 are in a vacuum state. Due to the pressure difference with the outside, the outer peripheral part of the disc-shaped recording carrier mold 2 is suction-pressed against the upper rotary table 1, and at the same time, the upper rotary table 1 is suction-pressed against the lower rotary table 7.

As described in the conventional example, the disc-shaped record carrier mold 2 has a signal recording area curved into a bowl shape. If the disc-shaped record carrier mold 2 having such a warp is attracted with a strong force, high-frequency distortion will occur because the wall thickness is extremely thin, and this will impede reproduction and inspection. When the entire surface of the disc-shaped record carrier mold 2 is clamped by vacuum suction, the pressing force is too strong, and the desired flatness cannot be obtained for the above-mentioned reasons. Here, by clamping by magnetic attraction, it is possible to press with an appropriate attraction force and obtain the desired flatness. Incidentally, the peripheral portion of the disc-shaped recording carrier mold 2 has distortion because it has undergone several peeling steps. Therefore, magnetic attraction cannot uniformly attract the peripheral area. If the rotary table were to be rotated in this state, uncorrected distortions remaining in the peripheral portion would act as a vibration source, which would impede reproduction and inspection. Therefore, it is necessary to press the periphery with strong force. Therefore, by pressing the periphery of the disk-shaped recording carrier mold 2 with a strong force by vacuum suction as in the embodiment of the present invention, it is possible to prevent vibrations that occur during rotation. At this time, by providing the vacuum seal rings 5a and 5b so that the vacuum suction force does not act on the signal recording area, only the peripheral portion can be vacuum suctioned.

In order to optically reproduce a disc-shaped record carrier mold, a laser beam is focused by an objective lens and irradiated onto the disc-shaped record carrier mold, and the reflected light is read. If it is out of the field of view of the lens, it cannot be played. Therefore, it is necessary to minimize the amount of eccentricity of the signal groove. Generally, in a disc-shaped record carrier mold, the positioning when drilling the center hole is not controlled with high precision, and the eccentricity of the signal groove with respect to the center hole may be large. In this embodiment, by aligning the positioning pin 11 with the positioning plate 10, the centers of the upper rotary table 1 and the lower rotary table 7 can be aligned. Here, if the amount of eccentricity between the center hole 2a of the disc-shaped record carrier mold 2 and the signal groove is small, reproduction and inspection are possible in this state, but if the amount of eccentricity is large, it is necessary to correct it to the desired amount. There is. Since the positioning pin 11 is normally pushed up by the leaf spring 12, a gap is created in the radial direction between the tip of the positioning pin 11 and the center hole 10a of the positioning plate 10. Therefore, the upper rotary table 1 is in a state where it can move in the radial direction within the range of the gap. Therefore,
While detecting the position of the signal groove, the upper rotary table 1 can be moved in the radial direction using a moving means provided outside to align the center of the signal groove with the center of the lower rotary table 7, that is, the center of the rotation shaft 13. can. After the eccentricity is corrected, the upper rotary table 1 is clamped to the lower rotary table 7 by vacuum suction, so that no positional deviation occurs.

In this embodiment, the vacuum suction means was provided outside the signal recording area, but depending on the disc-shaped record carrier mold, the position of the vacuum suction means is not limited to the outside, but may be provided inside the signal recording area. Moreover, it may be provided both inside and outside. In addition, in this embodiment, the center boss 9
is removable, and by replacing the center boss 9, it can be used with disk-shaped record carrier molds having different center hole diameters.

Effects of the Invention As described above, according to the present invention, the rotary table is divided into upper and lower halves, and the upper rotary table on which the disc-shaped record carrier mold is mounted is movable in the radial direction on the lower rotary table. By doing so, it is possible to correct the eccentricity of the signal groove of the disc-shaped record carrier mold. Further, after the eccentricity is corrected, by holding the upper rotary table on the lower rotary table by vacuum suction, it is possible to reliably hold the upper rotary table while maintaining the state in which the eccentricity has been corrected.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention,
FIG. 1 is a partially cutaway plan view, FIG. 2 is a longitudinal sectional view, and FIG. 3 is a sectional view of a disc-shaped record carrier mold. DESCRIPTION OF SYMBOLS 1...Upper rotary table, 2...Disc-shaped record carrier mold, 3...Rubber magnet disc, 4...Through hole, 6a,
6b...Exhaust groove, 7...Lower rotary table, 9...
Center boss, 10... Positioning plate, 11... Positioning pin, 12... Leaf spring.

Claims (1)

[Scope of Claims] 1. A rotary table for clamping a disc-shaped record carrier mold, an upper rotary table having means for holding the disc-shaped record carrier mold, and an upper rotary table for supporting and holding the upper rotary table. 1. A disk-shaped record carrier mold clamping device comprising: a lower rotary table having a means for clamping a disc-shaped record carrier mold; 2. A disc-shaped record carrier mold clamping device according to claim 1, wherein the upper rotary table is held on the lower rotary table by vacuum suction. 3. A disc-shaped record carrier mold clamping device according to claim 1, wherein the disc-shaped record carrier mold is held on the upper rotary table by vacuum suction. 4. A disc-shaped record carrier mold clamping device according to claim 1, wherein the disc-shaped record carrier mold is held on the upper rotary table by magnetic attraction.